when you look at ePO services (when you can't access web console) does the "Services Serveur d'applications McAfee ePolicy Orchestrator 4.6.2" service really appear as "started" or could it be stuck at "starting"?

Perhaps the problem isdue by other services starting during reboot that causes the "Serveur d'applications McAfee ePolicy Orchestrator 4.6.2" service to be unstable or not really started (even if appearing as started).

If you set them to be started manually and start them once you log into the server does it works? If so you may try to delay ePO's service start and see if it works (http://support.microsoft.com/kb/193888)